Hi,
From your description, I understood that you want to activate a license under a SVF stack that has already installed some licenses on it. When a license is loaded for SVF, you only need to load the license on the parent switch, not on the leaf switch.
Perform the following operations:
1. Apply for a license and upload it to the parent switch.
2. Run the license active file-name command in the user view to activate the license file you uploaded.
3. Run the display license command to check whether a license file has been loaded.
Is it true that there can be only one license file installed on the switches?
If so, will the SVF license be overwritten with the new license for the APs installed?
====== No, you can install multi licenses to enable the different functions.
What do I need to do to have this new license installed without overwriting the current SVF license and that this new license is valid for the stack?
====== You can even split the AP license and activate using each switch ESN or use a single license with all ESN activated.